The electronic industry continues to seek products that are lighter, faster, smaller, multi-functional, more reliable and more cost-effective. In an effort to meet such requirements, package assembly techniques have been developed for multi-chip packages (MCP) and chip stack packages. These types of packages combine two or more semiconductor chips in a single package, thereby realizing increased memory density, multi-functionality and/or reduced package footprint.
The use of several chips in a single package does, however, tend to reduce both reliability and yield. If, during post assembly testing, just one chip in the multi-chip or chip stack package fails to meet the functional or performance specifications, the entire package fails, causing the good chip(s) to be discarded along with the failing chip. As a result, multi-chip and chip stack package may lower the productivity from the assembly process.
A 3-dimensional package stack addresses this yield problem by stacking several assembled packages that each contain a single chip and that have already passed the necessary tests, thereby improving the yield and reliability of the final composite package. However, package stacks have tended to use lead frame type packages rather than area array type packages. Lead frame type packages typically utilize edge-located terminals such as outer leads, whereas area array type packages typically utilize surface-distributed terminals such as solder balls. Area array type package may therefore provide larger terminal counts and/or smaller footprints when compared with corresponding lead frame type packages.
Thus, a need still remains for an integrated circuit package system for package stacking. In view of the rate of development of consumer electronics and the insatiable demand for multi-function devices at low manufacturing costs, it is increasingly critical that answers be found to these problems. In view of the ever-increasing commercial competitive pressures, along with growing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace, it is critical that answers be found for these problems. Additionally, the need to save costs, improve efficiencies and performance, and meet competitive pressures, adds an even greater urgency to the critical necessity for finding answers to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.